Headspace schematic diagram

Figure 4.2 shows a typical schematic diagram for a headspace gas chromatographic (HSGC) instrumental setup. Typically, the analyte is... 

Figure 4.2. Schematic diagram of headspace extraction autosampler and GC instrument.

Figure 1. Schematic diagram of a retro-fit on-column injector used for the direct injection of headspace into a fused silica column, by means of a syringe fitted with a fused silica needle. A section of the column is chilled in liquid nitrogen during the injection, the Dewar flask is then removed, and the chromatogram commenced. Adapted from reference ( ), which should be consulted for additional details.

Automated Procedures Some of the difficulties associated with manual procedures can be eliminated with an automated headspace sampler. Such a device has been described in the literature (14), and is commercially available. The schematic diagram of such a semi-automatic headspace analyzer is shown in Figure 3. Precise control of times and temperatures, as well as the capability to hold samples at high temperatures, produces better chromatographic reproducibility. We have been able to analyze ppm levels of ethyl dodecanoate in aqueous solution with this system. Significant amounts of water vapor are introduced into the gas chromatographic column under these conditions. For this reason, columns with non-polar liquid phases or bonded Carbowax-type liquid phases... 

Figure 3.13. Schematic diagram of the balanced pressure sampling system for automated splitless static headspace gas chromatography with cryogenic trapping. V = solenoid valve in the carrier gas (CG) line V2 = solenoid valve for the purge gas and V3 solenoid valve for the cooling gas. (From ref. [142] Elsevier).

Fig. 9. Schematic diagram showing how heat transfer is typically modeled in a bioreactor with mixing and forced aeration. (1) Entry of sensible energy with the inlet air (2) Generation of waste heat by the microorganism (3) Mixing, which maintains equilibrium between the substrate bed and the headspace, and within each of these subsystems (4) Convective heat transfer from the bioreactor wall to the surroundings (5) Exit of sensible energy in the outlet air (6) Exit of the heat of vaporization of water in the outlet air, which is assumed to be saturated...

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